This invention relates to a flexible starter bar for use in continuous casting processes. The advantages of flexible starter bars over rigid starter bars have been described extensively in the patent literature and generally relate to labor and space-saving improvements in storing the starter bar.
Flexible starter bars normally comprise a series of links attached to each other by means which allow the bar to flex through bending rolls which lie in the path of movement of the strand and also through straightening rolls whereby the strand is straightened. Because of their flexibility, support rolls are also provided to maintain the starter bar in a curved configuration along the casting path. Chain type link structures, in particular, have been used extensively in the construction of flexible starter bars and most improvements to such structures are directed to minimizing and controlling any play between the links so as to prevent jerking strand motions which may result in molten metal breaking out of the mold.
A departure from the chain link structures general adopted in the industry is to provide a plate type starter bar formed by a relatively thin plate as in U.S. Pat. No. 4,660,616 and U.S. Pat. No. 3,889,740. These structures have not been adopted to any great extent and it is believed that no suitable material has been found which will have the necessary flexibility to withstand repeated flexings through the casting train, the strength to withstand the load of the strand, and the positional stability not to twist as the bar is drawn through the casting train.
To some extent these problems were alleviated in "sandwich" structures comprising top and bottom flat thin steel plates connected to each other by an intervening structure which could assume a variety of shapes as illustrated in a trilogy of patents issued earlier than the aforementioned plate type bars, namely U.S. Pat. Nos. 3,451,466; 3,603,375; and 3,633,653. These patents in turn were alleged to be improvements over flexible starter bars of the type in which a series of links were strung on a flexible tie rod as in U.S. Pat. No. 2,920,359. Other patents of this general class include U.S. Pat. Nos. 3,262,162; 3,351,125 and 3,442,322 in which the tie element is a bar or band. Presumably the improvement in the "sandwich" structures resides in providing a self-supporting bar and a continuous smooth surface which will minimize damage to rolls. There is however an attendant compromise with a reduction in flexibility.
An object of this invention is to provide a starter ba which is self-supporting and flexible.